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Mullowney D, Chang YM, Glanemann B, Syme HM. Treatment failure in hyperthyroid cats after radioiodine (I-131) injection. J Vet Intern Med 2021; 35:1688-1696. [PMID: 33999452 PMCID: PMC8295673 DOI: 10.1111/jvim.16161] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 04/29/2021] [Accepted: 05/03/2021] [Indexed: 12/17/2022] Open
Abstract
Background There is limited published information on the outcome for cats where total thyroxine concentration (TT4) remains elevated after treatment with radioactive iodine (RAI). Objective To determine the frequency of, and predictors for, subsequent treatment failure in cats for which TT4 remains elevated at hospital discharge, and to report clinical outcomes for cats requiring repeat treatment. Animals One hundred twenty‐one cats with TT4 ≥40 nmol/L after treatment with RAI (out of an original, treated study sample of 959 cats). Methods Retrospective study. Data regarding signalment, weight, TT4 concentration (before RAI treatment, at discharge, and percentage change), day of sampling, and I‐131 dose were acquired. Logistic regression was performed to evaluate predictors of treatment failure. Results In the 87 cats for which classification was possible, 35 (40%) became euthyroid without further treatment. All TT4 variables and weight normalized RAI dose were independently predictive of subsequent treatment failure. In multivariate analysis, TT4 concentration at discharge (P < .001) and weight normalized RAI dose (P = .04) remained in the final model. All 28 cats with TT4 concentration ≥150 nmol/L at discharge ultimately failed treatment, compared with 13/40 (32.5%) and 11/19 (57.9%) cats with TT4 concentrations of 40‐100 nmol/L and 100‐150 nmol/L, respectively. Of the 52 cats that failed treatment, 14 were subsequently managed medically, 12 underwent thyroidectomy (4 with carcinoma), 14 had repeat RAI treatment which was successful in 12/14 (86%) cats, and 13 had no further treatment. Conclusions and Clinical Importance Cats with TT4 >150 nmol/L at discharge after RAI might be candidates for immediate repeat treatment.
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Affiliation(s)
- Deirdre Mullowney
- Department of Veterinary Clinical Sciences, Royal Veterinary College, University of London, Hertfordshire AL9 7TA, United Kingdom
| | - Yu-Mei Chang
- Research Support Office, The Royal Veterinary College, London, United Kingdom
| | - Barbara Glanemann
- Department of Veterinary Clinical Sciences, Royal Veterinary College, University of London, Hertfordshire AL9 7TA, United Kingdom
| | - Harriet M Syme
- Department of Veterinary Clinical Sciences, Royal Veterinary College, University of London, Hertfordshire AL9 7TA, United Kingdom
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Wehner A, Koehler I, Ramspott S, Hartmann K. Relationship between total thyroxine, thyroid palpation and a clinical index in hyperthyroid and healthy cats and cats with other diseases. J Feline Med Surg 2019; 21:741-749. [PMID: 30328752 PMCID: PMC10814298 DOI: 10.1177/1098612x18799462] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVES Present-day diagnosis of hyperthyroidism is often established in the early stages where clinical signs and physical examination findings typically associated with the disease may not yet be present. The purpose of this study was to investigate thyroid palpation score (TPS), total thyroxine (T4), body weight, body condition score and a clinical scoring index, which assesses severity of illness and quality of life, in untreated hyperthyroid cats, healthy cats and cats with non-thyroidal illness. METHODS Fifty-five cats with hyperthyroidism, 45 healthy cats and 327 euthyroid cats with non-thyroidal disease were prospectively enrolled. A Kruskal-Wallis test was used to determine any differences between metric data. A χ2 test was applied to compare nominal data between the three subgroups. Correlation between two variables was analysed using Spearman's correlation coefficient. RESULTS Almost 80% of the hyperthyroid cats and up to 20% of the healthy cats and cats with non-thyroidal illness had a palpable thyroid gland. Median TPS in hyperthyroid cats was 2, which was significantly higher compared with the other groups. Although there was a significant correlation between TPS and T4 when evaluating all cats, this could not be demonstrated in the three subgroups. Hyperthyroid cats with larger thyroid glands (TPS >3) did not have higher T4 levels. Hyperthyroid cats with lower clinical scores had significantly higher T4 levels compared with hyperthyroid cats with higher scores. Hyperthyroid cats were older and had lower body weights and body condition scores than other cats. CONCLUSIONS AND RELEVANCE Hyperthyroid cats were commonly found to have palpable thyroid glands, but they were smaller than previously reported.
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Affiliation(s)
- Astrid Wehner
- Center of Clinical Veterinary Medicine, Clinic of Small Animal Medicine, Ludwig Maximilian University, Munich, Germany
| | - Ines Koehler
- Center of Clinical Veterinary Medicine, Clinic of Small Animal Medicine, Ludwig Maximilian University, Munich, Germany
| | - Sabine Ramspott
- Center of Clinical Veterinary Medicine, Clinic of Small Animal Medicine, Ludwig Maximilian University, Munich, Germany
| | - Katrin Hartmann
- Center of Clinical Veterinary Medicine, Clinic of Small Animal Medicine, Ludwig Maximilian University, Munich, Germany
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Covey HL, Chang YM, Elliott J, Syme HM. Changes in thyroid and renal function after bilateral thyroidectomy in cats. J Vet Intern Med 2019; 33:508-515. [PMID: 30758070 PMCID: PMC6430951 DOI: 10.1111/jvim.15450] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 01/28/2019] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Iatrogenic hypothyroidism might worsen the prognosis of cats with azotemic CKD after thyroidectomy. Varying thyroxine concentrations influence utility of creatinine in assessing renal function. Symmetric dimethylarginine (SDMA) has limited studies in cats with changing thyroid status. OBJECTIVES Thyroid status is stable 6 months post-thyroidectomy. Symmetric dimethylarginine and creatinine are linearly associated without influence from total thyroxine concentration (tT4). ANIMALS Electronic records of 2 first opinion practices were searched using the term "thyroidectomy" to include 81 client-owned cats that had undergone bilateral thyroidectomy. METHODS Retrospective cross-sectional study assessing thyroid hormone concentrations of 68 cats within 6 months of surgery. A longitudinal study of thyroid status in 23 cats with >18 months follow-up post-thyroidectomy. A generalized estimating equation assessed the associations of bodyweight, tT4 and creatinine concentrations on SDMA concentration. RESULTS Sixty-eight cats had follow-up within 6 months. Fifteen cats (22%) had persistent, or recurrent, hyperthyroidism and 33 cats (49%) were hypothyroid. Twenty-three of the euthyroid/hypothyroid cats had long-term follow-up (595-1955 days); 4 cats (17%) remained hypothyroid, 19 cats (83%) were euthyroid (often transiently), and 9 of 23 cats (44%) developed recurrent hyperthyroidism. Symmetric dimethylarginine and creatinine were linearly associated, but hyperthyroid cats had higher SDMA concentrations, relative to creatinine (P = .003). CONCLUSIONS AND CLINICAL IMPORTANCE Cats have changes in thyroid function for years after bilateral thyroidectomy, with a high incidence of recurrent hyperthyroidism. Both SDMA and creatinine are affected by thyroxine concentrations, and the effect is greater in hyperthyroid cats.
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Affiliation(s)
- Heather L Covey
- Department of Clinical Science and Services, Small Animal Medicine and Surgery Group, The Royal Veterinary College, Hertfordshire, United Kingdom
| | - Yu-Mei Chang
- Research Support Office, The Royal Veterinary College, London, United Kingdom
| | - Jonathan Elliott
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, London, United Kingdom
| | - Harriet M Syme
- Department of Clinical Science and Services, Small Animal Medicine and Surgery Group, The Royal Veterinary College, Hertfordshire, United Kingdom
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Morré WA, Panciera DL, Daniel GB, Monroe WE, Werre S. Investigation of a novel variable dosing protocol for radioiodine treatment of feline hyperthyroidism. J Vet Intern Med 2018; 32:1856-1863. [PMID: 30328158 PMCID: PMC6271315 DOI: 10.1111/jvim.15296] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 05/21/2018] [Accepted: 07/17/2018] [Indexed: 12/03/2022] Open
Abstract
Background Radioiodine is the treatment of choice for hyperthyroidism in cats. The ideal method of dose determination of radioiodine remains controversial. Objective To compare a method of radioiodine dose determination that utilized thyroid scintigraphy with a standard fixed dose for treatment of hyperthyroidism. Animals Fifty‐seven and 23 client‐owned hyperthyroid cats in the variable and fixed dose groups, respectively. Methods Cats with a percent dose uptake using 99mTc‐pertechnetate uptake on thyroid scintigraphy <5%, 5%‐10%, and >10% were to receive 3, 3.5, or 4.5 millicuries (mCi) of radioiodine, respectively, administered SC. Radioiodine dose was adjusted according to thyroid gland size as determined by the thyroid:salivary size ratio and categorized as <5:1, 5‐10:1, and >10:1. If the thyroid size fell into a higher dosing category than the percent dose uptake, the dose was increased accordingly. Cats in the fixed dose group received 4.5 mCi. Six months after treatment, cats were determined to be euthyroid, hypothyroid, or hyperthyroid based on serum thyroxine and thyroid stimulating hormone concentrations. Results No difference in outcome was found between the variable and fixed dose treatment groups. Euthyroidism, hypothyroidism, and persistent hyperthyroidism developed in 61, 30, and 9% of cats in the fixed dose group compared to 58, 26, and 16%, respectively, in the variable dose group. Conclusions A variable dosing method of radioiodine based on percent dose uptake primarily and thyroid gland size secondarily did not improve outcome compared to a standard fixed dose method.
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Affiliation(s)
- Wendy A Morré
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Blacksburg, Virginia
| | - David L Panciera
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Blacksburg, Virginia
| | - Gregory B Daniel
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Blacksburg, Virginia
| | - William E Monroe
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Blacksburg, Virginia
| | - Stephen Werre
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Blacksburg, Virginia
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Volckaert V, Vandermeulen E, Duchateau L, Daminet S, Saunders JH, Peremans K. Predictive value of scintigraphic (semi-)quantitative thyroid parameters on radioiodine therapy outcome in hyperthyroid cats. J Feline Med Surg 2018; 20:370-377. [PMID: 28689464 PMCID: PMC11129218 DOI: 10.1177/1098612x17713854] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
Objectives The outcome of radioiodine therapy in hyperthyroid cats is suspected to be influenced by multiple factors. The degree of activity of the thyroid gland, represented by uptake of sodium pertechnetate or tracer activities of radioiodine by the thyroid gland on thyroid scintigraphy, has been suggested in the literature as one of those. Thyroid gland pertechnetate uptake can be represented by (semi-)quantitative factors such as the thyroid to salivary gland (T/S) ratio, the thyroid to background (T/B) ratio and the percentage technetium uptake by the thyroid glands (%TcU). The aim of this study was to investigate a possible relationship between these thyroid scan parameters and radioiodine therapy outcome. Methods Sodium pertechnetate thyroid scans of 75 hyperthyroid cats were retrospectively evaluated and statistical analysis was performed with and without correction for injected radioiodine activity. Three different background regions of interest (ROIs) were used to calculate the T/B ratio and %TcU: 'neck', 'circle' and 'copy ROI'. Results Higher T/S ratios were found to be significantly related to a persistent hyperthyroid outcome in both analyses. For the T/S ratio, a threshold value of 5.4 was determined, with a sensitivity of 73% and a specificity of 59%. An increased risk for persistent hyperthyroidism compared with a final euthyroid outcome with an increased T/Bcircle ratio was only found to be significant without correction for the activity of radioiodine administered. For the %TcU no statistical significance was reached. Regarding a low total thyroxine outcome, no significant relationships with any of the investigated parameters were found. Conclusions and relevance The findings of this study suggest that semi-quantification of thyroid gland uptake is best performed using the T/S ratio. A T/S ratio ⩾5.4 is a possible indicator for an increased risk of persistent hyperthyroidism.
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Affiliation(s)
- Veerle Volckaert
- Faculty of Veterinary Medicine, Department of Small Animal Medical Imaging and Orthopaedics, Ghent University, Merelbeke, Belgium
| | - Eva Vandermeulen
- Faculty of Veterinary Medicine, Department of Small Animal Medical Imaging and Orthopaedics, Ghent University, Merelbeke, Belgium
| | - Luc Duchateau
- Faculty of Veterinary Medicine, Department of Comparative Physiology and Biometrics, Ghent University, Merelbeke, Belgium
| | - Sylvie Daminet
- Faculty of Veterinary Medicine, Department of Medicine and Clinical Biology of Small Animals, Ghent University, Merelbeke, Belgium
| | - Jimmy H Saunders
- Faculty of Veterinary Medicine, Department of Small Animal Medical Imaging and Orthopaedics, Ghent University, Merelbeke, Belgium
| | - Kathelijne Peremans
- Faculty of Veterinary Medicine, Department of Small Animal Medical Imaging and Orthopaedics, Ghent University, Merelbeke, Belgium
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Stock E, Daminet S, Paepe D, Buresova E, Vandermeulen E, Smets P, Duchateau L, Saunders JH, Vanderperren K. Evaluation of Renal Perfusion in Hyperthyroid Cats before and after Radioiodine Treatment. J Vet Intern Med 2017; 31:1658-1663. [PMID: 29031027 PMCID: PMC5697172 DOI: 10.1111/jvim.14852] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 08/05/2017] [Accepted: 09/13/2017] [Indexed: 12/28/2022] Open
Abstract
Background Hyperthyroidism and chronic kidney disease (CKD) are common in elderly cats. Consequently, both diseases often occur concurrently. Furthermore, renal function is affected by thyroid status. Because changes in renal perfusion play an important role in functional renal changes in hyperthyroid cats, investigation of renal perfusion may provide novel insights. Objectives To evaluate renal perfusion in hyperthyroid cats with contrast‐enhanced ultrasound (CEUS). Animals A total of 42 hyperthyroid cats was included and evaluated before and 1 month after radioiodine treatment. Methods Prospective intrasubject clinical trial of contrast‐enhanced ultrasound using a commercial contrast agent (SonoVue) to evaluate renal perfusion. Time‐intensity curves were created, and perfusion parameters were calculated by off‐line software. A linear mixed model was used to examine differences between pre‐ and post‐treatment perfusion parameters. Results An increase in several time‐related perfusion parameters was observed after radioiodine treatment, indicating a decreased blood velocity upon resolution of the hyperthyroid state. Furthermore, a small post‐treatment decrease in peak enhancement was present in the renal medulla, suggesting a lower medullary blood volume. Conclusions and Clinical Importance Contrast‐enhanced ultrasound indicated a higher cortical and medullary blood velocity and higher medullary blood volume in hyperthyroid cats before radioactive treatment in comparison with 1‐month post‐treatment control.
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Affiliation(s)
- E Stock
- Department of Medical Imaging of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - S Daminet
- Small Animal Department, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - D Paepe
- Small Animal Department, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - E Buresova
- Small Animal Department, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - E Vandermeulen
- Department of Medical Imaging of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - P Smets
- Small Animal Department, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - L Duchateau
- Department of Comparative Physiology and Biometry (Duchateau), Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - J H Saunders
- Department of Medical Imaging of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - K Vanderperren
- Department of Medical Imaging of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
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Peterson ME, Guterl JN, Rishniw M, Broome MR. EVALUATION OF QUANTITATIVE THYROID SCINTIGRAPHY FOR DIAGNOSIS AND STAGING OF DISEASE SEVERITY IN CATS WITH HYPERTHYROIDISM: COMPARISON OF THE PERCENT THYROIDAL UPTAKE OF PERTECHNETATE TO THYROID-TO-SALIVARY RATIO AND THYROID-TO-BACKGROUND RATIOS. Vet Radiol Ultrasound 2016; 57:427-40. [DOI: 10.1111/vru.12360] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 11/09/2015] [Accepted: 11/09/2015] [Indexed: 01/18/2023] Open
Affiliation(s)
- Mark E. Peterson
- Animal Endocrine Clinic; New York NY 10025
- Cornell University College of Veterinary Medicine; Ithaca NY 14853
| | | | - Mark Rishniw
- Cornell University College of Veterinary Medicine; Ithaca NY 14853
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